A helpful hint for helping your deck estimation skills for card steering or counting for that matter is, a chip is very close to the thickness of a 1/4 deck. So practice cutting however many cards suits your game, but chips are a good visual guideline, whether your cutting 13 or 52. Remember its just a visual training tool, you have to actually practice cutting to get the mechanics of it down. You should be right on more than 90% of the time and no more than 1 off the rest. If you can't achieve that type of accuracy don't try this with any kind of big betting as it will cripple your bankroll. It is opportunistic but there are still a few casinos in Vegas that don't cover the bottom card in their games, as well as other casinos in various other locations.
And remember cutting to the card is only half the game, getting good at steering the card to your hand or the dealers hand smoothly and naturally is a task that requires quite a bit of practice to do it correctly. It usually requires playing multiple hands and some basic strategy slip ups, all to be done to look natural, keeping in mind if you do have to play some hands incorrectly which ones to do it. Its a game with high variance, and not for the weak of heart if your going to play with big money, but also very lucrative if your good at it and get the chance to perform it often.